Protected areas worldwide are effectively keeping invasive animals away, but most of them are at risk of invasions, says the new study from the Chinese Academy of Science. Researchers assessed almost 200,000 protected areas worldwide and only 10% of them were found to host any of the 894 terrestrial animal invasive species surveyed. However, almost all these areas are at risk - invasive species were found within 100km of the boundaries of 99% of them.